URL Encoding is the process of converting the URL into a valid format that is accepted by web browsers. URL Encoding takes place by replacing all the characters that are not allowed by a % sign followed by two hexadecimal digits. These two hexadecimal values represent the numerical values of the character in the ASCII character set. For example, a space is not acceptable in a URL and is replaced by ‘%20’ or a ‘+’ sign while encoding. Similarly, a $ sign is replaced by ‘%24’.

Reserved Characters:

There are certain characters that sometimes have special meanings in the URL and it can be used in both ways. For example, the ‘/’ character is a reserved character and it has a special meaning when being used as a delimiter to separate the paths of a URL.

Free Resources

https://www.geeksforgeeks.org/html-url-encoding/
https://www.w3schools.com/tags/ref_urlencode.asp